Cooling liquid admitting and exhausting device for use with liquid-cooled electrical rotary machines

ABSTRACT

A cooling liquid admitting and exhausting device for liquidcooled electrical rotary machines for admitting a cooling liquid from a stationary member into a rotary member and exhausting the liquid from the rotary member into the stationary member or vice versa, in which a cover assembly is so arranged as to enclose therein through sealing means a hollow rotary shaft having therein a cooling liquid admitting and exhausting passages, rotatably supported by said shaft through bearing means, and capable of following every movement of the shaft in the axial direction and vibrations thereby to positively prevent the leakage of the liquid.

United States Patent Inventors Hiroshi Sato;

Satoshi Suzuki, Hitachi-shi, Japan Appl. No. 877,795 Filed Nov. 18, 1969 Patented Mar. 23, 1971 Assignee Hitachi, Ltd.

Tokyo, Japan Priority Nov. 25, 1968 Japan 43/85595 COOLING LIQUID ADMITTING AND EXHAUSTING DEVICE FOR USE WITH LIQUID- COOLED ELECTRICAL ROTARY MACHINES Primary Examiner-D. F. Duggan Attorney-Craig, Antonelli, Stewart & Hill ABSTRACT: A cooling liquid admitting and exhausting device for liquid-cooled electrical rotary machines for admitting a cooling liquid from a stationary member into a rotary member and exhausting the liquid from the rotary member into the stationary member or vice versa, in which a cover assembly is so arranged as to enclose therein through sealing means a hollow rotary shaft having therein a cooling liquid admitting and exhausting passages, rotatably supported by said shaft through bearing means, and capable of following every movement of the shaft in the axial direction and vibrations thereby to positively prevent the leakage of the liquid.

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INVENTORS HIRoSHI d SATOSHIL' Suzuki 1; MW q 340 (7' ATTORNEYS PATENTED was 1971 SHEET 2 OF 3 INVENTOR 5 HIKDSHI SATO 4nd BATOSHIL' Suz L447, "I M ATTORNEYS PATENTED M2319?! 57' 1 634 sum 3 OF 3 INVENTOR5 IIIROSHI SATo and SATI'OSHI Sun/ ATTORNEYS COOLING LIQUID ADMITTING AND EXHAUSTING DEWCE FOR USE WITH LIQUID-COOKED ELECTRICAL ROTARY MACHINES BACKGROUND OF THE INVENTION i In this case, one of the most important factors in increasing their capacities is to provide a very efficient cooling system. In many conventional generators, gas cooling system such as hydrogen cooling has been generally employed, but it is preferable to employ a liquid cooling system which has a better cooling efficiency and a higher cooling capacity as compared with the gas cooling system. It is more preferable to cool not only the stators but also the rotors by this liquid cooling system. In the liquid cooling system, water, oil and any other suitable liquid may be used as cooling liquid, but water exhibits the highest cooling efficiency especially when the water is used to directly cool the hollow conductors of the generators and the like. However, in order to provide a liquid cooling system of the character described above, various important and difficult problems encountered in the construction, production, installation, etc., of the cooling system itself and the problem of coupling a stationary member to a rotary member must be solved.

The present invention contemplates to solve the problem of a cooling liquid admitting and exhausting device for admitting the cooling liquid into a rotary member from a stationary member and exhausting the liquid from the rotary member into the stationary member or vice versa among the abovedescribed various problems. It is most preferable to admit and exhaust the cooling liquid at the end of the rotor shaft on the side of the exciter because in the large capacity generators, the exciter is not directly coupled to the rotor shaft so that the end of the rotor shaft is free or available for this purpose.

In order to admit the cooling liquid into the rotor, that is the winding thereof, the rotor shaft is generally provided with a cooling liquid admitting passage and a cooling liquid exhausting passage formed therein in coaxial relation therewith. In most cases, an inner hollow cylinder is disposed coaxially in the hollow rotary shaft so as to provide the interior of the inner cylinder as for example the admitting passage and the space between the inner cylinder and the inner surface of the hollow rotary shaft as for example the exhausting passage.

At the free end of the rotor shaft is positioned a cover assembly so as to enclose said admitting and exhausting passages separately within the assembly and serve as a coupling between the rotary and stationary members.

In this case, there a very difficult problem of maintaining the liquidtightness of the cooling liquid circuit against the exterior. It is well known in the art that the cooling liquid used must not be electrically conductive, but the liquid-tightness of the liquid circuit is also very important and difficult especially where the rotary member contacts with the stationary member through the cooling system. It is rather impossible to mechanically liquid-tightly couple the rotary member with the stationary member. Mechanical seal is simple in construction and reliable in operation because it provides the sliding contact between the two members to be rotatably connected with each other while providing also the liquid-tightness therebetween. Mechanical seal is such that a stepped portion or an annular flange is formed at a suitable. portion of a rotor shaft and fitted slidably into an annular member of a fixed member, thereby providing the sealing depending upon the rubbing contact of the outer peripheral side surface of the stepped portion or the flange of the rotor shaft with the inner surface of the annular member of the fixed member. However,

the rotor shaft will not necessarily rotate at a predetermined position. For example, in case of a vertical-type water wheel generator, the rotor shaft makes vibrating displacement in the axial direction thereof relative to the fixed member due to the displacement of the bracket of the rotor frame due to the variation in the water pressure load so that the abovedescribed rubbing contact will not be ensured, thereby causing the leakage of the cooling liquid. Furthermore, the liquidtight sealing of the type described above is easily susceptible to breakdown because of the unbalance of the rotor and the rotor shaft due to the inaccurate machining and assembly thereof. The mechanical seal has some defects as described above and the ideal mechanical seal is such that a rotary member may be rotatably arranged with respect to a fixed member without any leakage therebetween even after a long operation time and the seal is simple in construction and capable of being produced without requiring a higher degree of accuracy.

SUMMARY OF THE INVENTION Accordingly, one of the objects of the present invention is to provide a cooling liquid admitting and exhausting device for use with rotary machines of the type described hereinabove which can eliminate any serious leakage of the cooling liquid when the cooling liquid circuits of a rotary member and a fixed member are coupled with each other.

Another object of the present invention is to provide a cooling liquid admitting and exhausting device of the type described which can sufficiently prevent the leakage of the cooling liquid from the cooling liquid circuits even when the rotary member is displaced in every direction relative to the fixed member.

A further object of the present invention is to provide a cooling liquid admitting and exhausting device of the type described which is simple in construction, easy to manufacture and assemble without requiring a higher degree of accuracy.

The novel features which are believed to be characteristic of the present invention are that the device of the present invention comprises a rotor shaft carrying a rotor and having a cooling liquid admitting passage and a cooling liquid exhausting passage formed therein, a cover assembly adapted to enclose therein said admitting and exhausting passages and means interposed between said rotary shaft and said cover as sembly for liquid-tightly sealing said cover assembly and that said cover assembly has bearings fitted upon said rotor shaft so as to be supported rotatably by said rotor shaft.

The above and other objects, features and advantages of the present invention will become more apparent from the following description of one illustrative embodiment thereof with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal section view of one embodiment of a cooling liquid admitting and exhausting device in accordance with the present invention applied to a vertical-type electrical rotary machine;

FIG. 2 is an exploded perspective view of sealing means used therein;

FIG. 3 is a perspective view of rotation preventive means for preventing the rotation of a cover assembly thereof; and

FIG. 4 is a diagrammatic view illustrating a cooling liquid circuit.

DESCRIPTION OFTI'IE PREFERRED EMBODIMENT Referring to FIG, I, a cooling fluid admitting and exhausting device comprises a cover assembly generally designated by l, a cooling liquid admitting and exhausting shaft 2, a rotor shaft 3, a liquid supply pipe 4 and a liquid exhaust or drain pipe 5. The rotor shaft 3 is coupled to a rotor (See FIG. 4) of a vertical type generator.

The rotary shaft 3 has an inner hole 30 for admitting the cooling liquid and an outer hole 31 for exhausting the cooling liquid. It is understood that the inner hole may be used for exhausting the cooling liquid while the outer hole may be used for admitting the cooling liquid. The former arrangement, however, is preferable because a pump (81, in FIG. 4) may have a less capacity in order to supply the cooling liquid from the exterior source of supply due to the centrifugal pumping action caused by the rotation of the rotor shaft 3. It is understood that it is not necessarily required that the cooling liquid admitting and exhausting holes are in coaxial relation with each other and with the axis of the rotor shaft 3 and that two holes may be drilled into the shaft 3 in side-by-side relation. In the instant embodiment, the cooling liquid admitting and exhausting holes or passages 34) and 31 are partitioned from each other by means of an inner cylinder 32 which in turn is held in position within the shaft 3 by means of a suitable supporting element 33 interposed between the inner cylinder 32 and the inner surface 34 of the shaft 3.

The expansion of the supporting element 33 in the axial direction presents no serious problem, but it is preferable that the thickness of the supporting element 33 be as thin as possible because of the consideration of the flow resistance of the cooling liquid passing therethrough. Both of the admitting and exhausting passages 30 and 31 extend downwardly toward the rotor and radially extend through the rotor, thus communicating hydraulically with the hollow conductor winding 91 in FIG. 4.

To the upper end of the rotor shaft 3 is connected the cooling liquid admitting and exhausting shaft 2 by means of suitable fastening means such as bolts and nuts. It is however understood that it is not necessary to form the admitting and exhausting shaft 2 independently of the rotor shaft 3, but it may be the extension of the shaft 3. But in view of the manufacturing steps and the transportation it is preferable to form the admitting and exhausting shaft 2 independently of the rotor shaft 3. As in the case of the rotor shaft 3, the admitting and exhausting shaft 2 has an inner and outer coaxial holes so as to provide the cooling liquid admitting passage 20 and the cooling liquid exhausting passage 21 both of which are hydraulically coupled to the passages 30 and 31 of the rotor shaft 3 respectively. The shaft 2 has an inner cylinder 22 which is held in position by means of a supporting element 23 and provides the partition between the admitting and exhausting passages 20 and 2i. The inner cylinder 22 is extended upwardly beyond the upper end of the admitting and exhausting shaft 2, and the upper end of the inner cylinder 22 is beveled as at 26. The upper end of the admitting and exhausting shaft 2 is also beveled as shown at 25 in order to reduce the resistance of the cooling liquid entering into the shaft 2.

The cover assembly 1 is fixed to the admitting and exhausting shaft 2 so as to enclose it within the assembly 1. To facilitate the manufacture and assembly of the cover assembly 1, it is preferable that it consists of a plurality of divided sections. In the instant embodiment the cover assembly 1 consists ofa cooling liquid supply or admitting box 10, a cooling liquid exhausting box ll, a leakage liquid collecting box 12 and a bearing box 13, which is arranged immediately above the upper end of the admitting and exhausting shaft 2 in order to reduce the vibrations of the cover assembly l to be described in more detail hereinafter and has bearings 14 interposed between the shaft 2 and the bearing box 13. Any bearing such as ball bearings and so on may be selected, but the ball bearings are preferable in view of the lubrication. Thus it is seen that the bearing box 13 is rotatably supported upon the admitting and exhausting shaft 2 through bearings 14. In the instant embodiment, two bearings 14 are spaced apart vertically from each other by a suitable distance because the bearing box 13 may be stabilized, but only one bearing may be employed. A sealing ring 15 is provided in order to seal the interior of the bearing box 13 from the exterior. The bearings 14 also support the leakage liquid collection box 12, the exhausting box 11 and the admitting box 10 through the bearing box 13.

The leakage liquid collection box 12 consists of an inner wall 41 arranged upon an annular base plate 40 in coaxial relation with the admitting and exhausting shaft 2 and an outer wall 42 arranged outwardly of the inner wall 411. The space defined by the inner and outer walls at and 42 is connected to a leaking liquid drain pipe 43. The leakage liquid collection box 12 is connected to the bearing box 13 at the annular base plate 40 by suitable fastening means and a flange portion M extending from the upper edge of the outer wall 62 supports thereupon the exhausting box ill.

The exhausting box 11 encloses the admitting and exhausting shaft 2 except the connection of the inner cylinder 22 to the admitting box 10. For this purpose, the exhausting box II is provided with a hole through which extends the inner cylinder 22. At both ends of the exhausting box ll, the box II is fitted over the shaft 2 and the inner cylinder 22 through sealing means 50 and 51 respectively in order to prevent the leakage of the cooling liquid.

The sealing means 50 and 51 may be equal in construction but different in the directions of their arrangement.

As best shown in FIG. 2, the sealing means 50 comprises a spring mounting disc 52 fitted over the inner cylinder 22 for rotation therewith, a sealing member 53 adapted to rotate together with the inner cylinder 22 because of the engagement with pins 59 extended from the disc 52, said sealing member 53 being slidable in the axial direction, a fixed disc 54 securely fixed to or formed integral with the exhausting box ill and in contact with the sealing member 53 and compression springs 55 loaded between the sealing member 53 and the supporting ring 52, whereby the sealing member 53 is normally pressed against the fixed ring or disc 54 by means of the springs 55, thereby water-tightly sealing the interior of the exhausting box 11 against the interior of the admitting box 10. The other sealing means 51 has the same construction as that of the sealing means 50 described hereinabove and seals the exhausting box 11 from the leakage liquid collection box 12.

Thus the exhausting box 11 having the rotary members therein can be sealed and the liquid of the admitting box ll leaking through the sealing means 50 flows into the exhausting box 11, but will not leak out of the device so that the sealing means 50 is not required to be machined and assembled with a higher degree of accuracy. However, in case of the leakage preventive means 51 must be machined with a higher degree of accuracy because the liquid which leaks through this means 51 flows out of the device.

To the admitting box 10 is connected the supply pipe 4 which in turn is hydraulically connected to the pump 81 in FIG. 4 while to the exhausting box 11 is connected a drain pipe 5 which in turn is communicated with a liquid reservoir in FIG. 4. Both of the supply and discharge pipes 4 and 5 are connected to the device throughflexible coupling members 60 and 61 such as rubber hoses or bellows respectively so that the cover assembly I may be displaced and rocked more or less. Such flexible coupling members as described above are interposed between the cover assembly 1 and the parts which are mechanically coupled thereto. For example, the discharge pipe 43 is coupled to the device through the flexible coupling member 62.

In order to prevent the rotation of the cover assembly 1 through a relatively larger angle of rotation even though the assembly I may be more or less displaced or rotated within a relatively small range, rotation preventive means is provided. The rotation preventive means is designated generally by reference numeral 70 in FIG. 3 and comprises a bifurcated member 72 securely fixed to the annular base plate il) by welding or by any suitable fastening means such as bolts and nuts and a stopper 73 fixed to a stationary member such as stator 74 of the generator and adapted to fit into the bifurcated portion. The stopper 73 comprises a pin '73 and an elastic body 76 surrounding the pin 75, so that the impact caused by the rotation of the cover assembly 1 may be damped or cushioned.

The rotation of the cover assembly l may be prevented in the directions indicated by the broken arrows by the stopper 70 fitted into the recess of the bifurcated member 72 while the vertical displacement of the cover assembly 1 may be permitted in the directions indicated by the solid-line arrows because there is a gap between the stopper 73 and the bifurcated member 72. instead of the rotation preventive means of the construction described hereinabove, any other suitable means well known in the art may be employed, but care should be exercised so as to prevent the impact due to the rotation from exerting upon the cover assembly It too suddenly because the rotation preventive means 70 must be so arranged as to provide a small gap between for example the stopper 73 and the bifurcated member 72 so that the cover assembly it may be vertically displaced but not rotated.

Next the mode of operation will be described with particular reference to FIG. 4. The admitting and exhausting shaft 2 coupled drivingly to the rotor 90 of the generator is rotating while the cooling liquid is flowing in the direction indicated by the arrows. That is, the cooling liquid is supplied from the reservoir 80 by means of the feed pump 81 and passes through the filter 82 and reaches the admitting box 10. Then, the cooling liquid flows through the admitting passage inside the inner cylinder 22 of the admitting and exhausting shaft 2 into the hollow portion of the hollow conductor winding 91, thereby cooling the winding 91. Thereafter, the cooling liquid returns to the shaft 2, flows through the exhausting passage 21, the exhausting box 11 and the drain pipe 5 to the reservoir 80.

The liquid leaked through the leakage preventive means 51 from the exhausting box 11 is collected in the leakage liquid collection box 12 and returned to the reservoir 80 through the drain pipe 85.

Thus the rotor of the generator may be sufficiently cooled, but the cover assembly 1 is arranged at the position at which the rotary member contacts with the stationary member so that there arises a very difficult problem regarding to the maintenance of the liquid-tightness. The cooling liquid admitting and exhausting shaft 2 is moving in all directions all the time because of the displacement in the axial direction of the rotor shaft 3 by the thermal expansion, the vibrations and vibrational displacement of the shaft 3 due to the variation in load applied thereto. Therefore, if the leakage preventive or sealing means 55) and 51 fail to follow these displacements and vibrations, the liquid-tightness of the cover assembly 1 is not ensured; the shaft 2 is subjected to the wear and abrasion; and a reliable operation for a longer period will not be ensured, However, these problems can be completely solved by the provision of the sealing means 50 and 51 according to the present invention.

Referring back to FIG. 1, the cover assembly 1 is rotatably carried upon the admitting and exhausting shaft 2 through the bearing M and mechanically coupled to the stationary member through the flexible means, so that when the admitting and exhausting shaft 2 is caused to displace and rotate due to the displacement, vibrations, etc. of the rotor shaft 3, the cover assembly ll can follow every movement of the shaft 2, whereby the sealing means 50 and 51 can be securely held in position all the time thereby maintaining positively the liquid-tightness of the cover assembly 1 all the time. F urthermore, because of the provision of a plurality of bearings 14 spaced apart from each other in the axial direction at the lower portion of the shaft 2, that is the portion which is least subjected to the vibrations, the vibrations of the cover assembly ll can be reduced to the minimum so that the leakage of the cooling liquid can be further ensured.

From the foregoing, it is seen that according to the present invention since the cover assembly 1 of the cooling liquid admitting and exhausting device is carried upon the rotor shaft by means of bearing means, the sealing means attached to the cover assembly may satisfactorily follow every movement of the rotor shaft while contacting therewith with the substantially constantpressure all the time so that the liquid-tightness is ensured and the leakage of the cooling liquid can be positively prevented. Thus, the sealing means are not required to be machined with a higher degree of accuracy so that the cumbersome manual fitting works and so on may be advantageously eliminated in the course of the production, and the installation is also facilitated.

The present invention has been so far described with particular reference to the embodiment thereof suited for use with the vertical-type electrical rotary machines, but it is understood that the present invention may be applied to the horizontal-type rotary machines. In the case, for example the leakage liquid collection box 12 must be modified more or less so that it may collect the leakage liquid when it is arranged horizontally. The cooling liquid admitting and exhausting device in accordance with the present invention may be also interposed intermediate of the rotary shaft instead of being arranged at one end thereof. In this case, the special arrangement of the bearings 14 may be required. However, in every case, it is preferable to provide a plurality of bearings spaced apart from each other by a distance as long as possible in the axial direction of the rotor shaft so that the cover assembly 1 may be securely held in stabilized position. In the embodiment described above, the cooling liquid admitting and exhausting passages have been described as being the coaxial holes formed in the admitting and exhausting shaft 2 and the rotor shaft 3, but these passages may be two juxtaposed holes in the shafts as described hereinabove.

The cooling liquid admitting and exhausting device in accordance with the present invention may be employed both in the vertical and horizontal-type electrical rotary machines. It is apparent from the foregoing description that the device of the present invention can positively prevent the leakage of the cooling liquid even when the rotor shaft is displace in the axial direction and vibrated, and has a relatively simple construction so that the device can be manufactured and assembled in a simple manner without requiring high techniques and skilled operators.

The present invention has been described so far with particular reference to one illustrative embodiment thereof, but is is understood that variations and modifications can be effected without departing from the true spirit of the present invention as described hereinabove and as defined in the appended claims.

We claim:

1. A cooling liquid admitting and exhausting device for use with liquid-cooled electrical rotary machines comprising a rotor having a hollow conductor winding,

a hollow rotor shaft carrying said rotor and having a cooling liquid admitting passage and a cooling liquid exhausting passage which are formed within said rotor shaft and in hydraulical communication with said hollow conductor winding,

a cover assembly enclosing therein the end portion of said rotor shaft and having a plurality of chambers in communication with said cooling liquid admitting and exhausting passages respectively, and

means interposed between said cover assembly and said rotor shaft for sealing each of said plurality of chambers from each other and from the exterior of said device; and

said cover assembly having a plurality of bearing means fitted upon said rotor shaft so as to rotatably support said cover assembly upon said rotor shaft.

2. A cooling liquid admitting and exhausting device as set forth in claim 1 wherein said bearing means comprises a plurality of bearings spaced apart from each other in the axial direction of said rotor shaft by a predetermined distance.

3. A cooling liquid admitting and exhausting device as set forth in claim 1 wherein said bearing means are arranged at the remote side from the end of said rotor shaft within said cover assembly.

4. A cooling liquid admitting and exhausting device as set forth in claim 1 wherein the stationary parts exterior of said device are coupled to said cover assembly through at least one flexible member so as to allow the slight movement of said cover assembly.

5. A cooling liquid admit ti n g and exhausting device as set forth in claim 1 wherein said cover assembly is coupled to a stationary member through a rotation preventive means comprising a pin-shaped stopper extending from said stationary member in the axial direction of said rotor shaft and having an elastic surface and a bifurcated member securely fixed to said cover assembly and adapted to receive said stopper in the bifurcated portion thereof, whereby said cover assembly is permitted to move in the axial direction but is elastically prevented from being rotated.

6. A cooling liquid admitting and exhausting device for use with liquid-cooled electrical rotary machines comprising a rotor having hollow conductive winding,

a hollow rotor shaft carrying said rotor and having a cooling liquid admitting passage and a cooling liquid exhausting passage which are in hydraulically communication with said hollow conductor winding of said rotor,

a cooling liquid admitting and exhausting shaft having a cooling liquid admitting passage and cooling liquid exhausting passage which are adapted hydraulically connected to said admitting and exhausting passages of said rotor shaft respectively when said second-mentioned shaft is coupled to said first-mentioned shaft,

a cooling liquid exhausting box enclosing therein said cooling liquid exhaust passage of said second-mentioned shaft at the end portion thereof remote from said first-mentioned shaft and having sealing means which are interposed between said second-mentioned shaft and said exhausting box in spaced-apart relation with each other in the axial direction in order to prevent the leakage of the cooling liquid from said exhausting box and a exhaust pipe for exhausting the cooling liquid from said exhausting box,

a cooling liquid admitting box securely fixed to said exhausting box so as to enclose therein said admitting passage of said second-mentioned shaft and having a cooling liquid supply pipe,

a leakage liquid collection box fixed to said exhausting box at the side opposite to said admitting box and having a drain pipe,

a bearing box securely fixed to said leakage liquid collection box at the side opposite to said exhausting box and having a plurality of bearings fitted over said second-mentioned shaft, thereby supporting said admitting box, said exhausting box and said leakage liquid collection box upon said second-mentioned shaft through said bearings; and

rotation preventive means fixed to at least one of said boxes. 

1. A cooling liquid admitting and exhausting device for use with liquid-cooled electrical rotary machines comprising a rotor having a hollow conductor winding, a hollow rotor shaft carrying said rotor and having a cooling liquid admitting passage and a cooling liquid exhausting passage which are formed within said rotor shaft and in hydraulical communication with said hollow conductor winding, a cover assembly enclosing therein the end portion of said rotor shaft and having a plurality of chambers in communication with said cooling liquid admitting and exhausting passages respectively, and means interposed between said cover assembly and said rotor shaft for sealing each of said plurality of chambers from each other and from the exterior of said device; and said cover assembly having a plurality of bearing means fitted upon said rotor shaft so as to rotatably support said cover assembly upon said rotor shaft.
 2. A cooling liquid admitting and exhausting device as set forth in claim 1 wherein said bearing means comprises a plurality of bearings spaced apart from each other in the axial direction of said rotor shaft by a predetermined distance.
 3. A cooling liquid admitting and exhausting device as set forth in claim 1 wherein said bearing means are arranged at the remote side from the end of said rotor shaft within said cover assembly.
 4. A cooling liquid admitting and exhausting device as set forth in claim 1 wherein the stationary parts exterior of said device are coupled to said cover assembly through at least one flexible member so as to allow the slight movement of said cover assembly.
 5. A cooling liquid admitting and exhausting device as set forth in claim 1 wherein said cover assembly is coupled to a stationary member through a rotation preventive means comprising a pin-shaped stopper extending from said stationary member in the axial direction of said rotor shaft and having an elastic surface and a bifurcated member securely fixed to said cover assembly and adapted to receive said stopper in the bifurcated portion thereof, whereby said cover assembly is permitted to move in the axial direction but is elastically prevented from being rotated.
 6. A cooling liquid admitting and exhausting device for use with liquid-cooled electrical rotary machines comprising a rotor having hollow conductive winding, a hollow rotor shaft carrying said rotor and having a cooling liquid admitting passage and a cooling liquid exhausting passage which are in hydraulically communication with said hollow conductor winding of said rotor, a cooling liquid admitting and exhausting shaft having a cooling liquid admitting passage and cooling liquid exhausting passage which are adapted hydraulically connected to said admitting and exhausting passages of said rotor shaft respectively when said second-mentioned shaft is coupled to said first-mentioned shaft, a cooling liquid exhausting box enclosing therein said cooling liquid exhaust passage of said second-mentioned shaft at the end portion thereof remote from said first-mentioned shaft and having sealing means which are interposed between said second-mentioned shaft and said exhausting box in spaced-apart relation with each other in the axial direction in order to prevent the leakage of the cooling liquid from said exhausting box and a exhaust pipe for exhausting the cooling liquid from said exhausting box, a cooling liquid admitting box securely fixed to said exhausting box so as to enclose therein said admitting passage of said second-mentioned shaft and having a cooling liquid supply pipe, a leakage liquid collection box fixed to said exhausting box at the side opposiTe to said admitting box and having a drain pipe, a bearing box securely fixed to said leakage liquid collection box at the side opposite to said exhausting box and having a plurality of bearings fitted over said second-mentioned shaft, thereby supporting said admitting box, said exhausting box and said leakage liquid collection box upon said second-mentioned shaft through said bearings; and rotation preventive means fixed to at least one of said boxes. 